Air conditioner

ABSTRACT

A refrigerant circuit performs a cool storage operation in which a thermal storage medium is circulated such that a refrigerant having been condensed in an air heat exchanger and passed through an auxiliary heat exchanger is evaporated in the thermal storage heat exchanger. In a thermal storage circuit during the cool storage operation of the refrigerant circuit, the thermal storage medium is circulated such that the thermal storage medium having flowed out from an outlet of a thermal storage tank sequentially passes through the auxiliary heat exchanger, a retention portion, and the thermal storage heat exchanger and flows into an inlet of the thermal storage tank. The retention portion retains crystals contained in the thermal storage medium.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2013-205695 filed on Sep. 30, 2013, the entire disclosure of which isincorporated by reference herein.

BACKGROUND

Storing heat using thermal storage properties of a thermal storagemedium, and utilizing the heat stored in the thermal storage medium fordriving an air conditioner, for example, have been known. As an exampleof such a thermal storage medium, a thermal storage material which turnsinto slurry when cooled (e.g., a tetra-n-butyl ammonium bromide aqueoussolution) has been known. For example, Japanese Unexamined PatentPublication No. 2013-083439 discloses an air conditioning system inwhich a thermal storage circuit is formed by connecting a thermalstorage tank in which a thermal storage medium is stored, and a thermalstorage heat exchanger incorporated in the refrigerant circuit. In thisair conditioning system, a cool storage mode is performed in which arefrigerant is circulated in the refrigerant circuit such that therefrigerant condensed in a condenser is evaporated in the thermalstorage heat exchanger, and in which the thermal storage medium iscirculated in the thermal storage circuit such that the thermal storagemedium having flowed out from an outlet of the thermal storage tankpasses through the thermal storage heat exchanger and flows in an inletof the thermal storage tank. In the cool storage mode, the thermalstorage medium passing through the thermal storage heat exchanger turnsinto slurry by being cooled due to heat absorption effects of therefrigerant passing through the thermal storage heat exchanger, andthereafter flows in the inlet of the thermal storage tank. Cold thermalenergy (i.e., energy for cooling) is stored in the thermal storagemedium in this manner.

Further, Japanese Unexamined Patent Publication No. H10-185248 disclosesa preheater which applies heat to cold water having been transferredfrom an ice thermal storage tank via a cold water circulation pump,using a refrigerant flowing from a condenser to an expansion valve, inorder to melt ice mixed in the cold water and discharge only cold water.

SUMMARY

According to an aspect of the present disclosure, an air conditionerincludes: a refrigerant circuit having an air heat exchanger whichexchanges heat between a refrigerant and air; a thermal storage circuithaving a thermal storage tank configured to store a thermal storagemedium which turns into slurry when cooled, and a circulation pumpprovided to circulate the thermal storage medium; a thermal storage heatexchanger which is connected to the refrigerant circuit and to thethermal storage circuit, and exchanges heat between the refrigerantflowing in the refrigerant circuit and the thermal storage mediumflowing in the thermal storage circuit; an auxiliary heat exchangerwhich is connected to the refrigerant circuit and to the thermal storagecircuit, and exchanges heat between the refrigerant flowing in therefrigerant circuit and the thermal storage medium flowing in thethermal storage circuit; and a retention portion provided in the thermalstorage circuit to retain crystals contained in the thermal storagemedium. The refrigerant circuit performs a cool storage operation inwhich the refrigerant is circulated such that the refrigerant which hasbeen condensed in the air heat exchanger and passed through theauxiliary heat exchanger is evaporated in the thermal storage heatexchanger. In the thermal storage circuit during the cool storageoperation, the thermal storage medium is circulated such that thethermal storage medium having flowed out from an outlet of the thermalstorage tank sequentially passes through the auxiliary heat exchanger,the retention portion, and the thermal storage heat exchanger and flowsinto an inlet of the thermal storage tank.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a piping system diagram illustrating an example configurationof an air conditioner.

FIG. 2 is a schematic view illustrating an example configuration of aretention portion.

FIG. 3 is a piping system diagram illustrating a cool storage mode ofthe air conditioner.

FIG. 4 is a piping system diagram illustrating a first use cooling modeof the air conditioner.

FIG. 5 is a piping system diagram illustrating a second use cooling modeof the air conditioner.

FIG. 6 is a piping system diagram illustrating a simple cooling mode ofthe air conditioner.

FIG. 7 is a piping system diagram illustrating a simple heating mode ofthe air conditioner.

FIG. 8 is a graph illustrating a temperature change of a thermal storagemedium in a thermal storage circuit.

FIG. 9 is a schematic view illustrating the first variation of theretention portion.

FIG. 10 is a schematic view illustrating the second variation of theretention portion.

FIG. 11 is a schematic view illustrating another variation of theretention portion.

FIG. 12 is a piping system diagram illustrating a variation of arefrigerant circuit.

DETAILED DESCRIPTION

Embodiments will be described in detail below with reference to thedrawings. In the drawings, like reference characters have been used todesignate identical or equivalent elements, and explanation thereof isnot repeated.

[Air Conditioner]

FIG. 1 shows an example configuration of an air conditioner (1)according to an embodiment. The air conditioner (1) includes arefrigerant circuit (10), a thermal storage circuit (20), a thermalstorage heat exchanger (30), an auxiliary heat exchanger (40), aretention portion (50), and a controller (100). The controller (100) isconfigured to control operation of the air conditioner (1), and controlseach section of the refrigerant circuit (10) and the thermal storagecircuit (20).

<Refrigerant Circuit>

The refrigerant circuit (10) is a closed circuit filled with arefrigerant, and performs a refrigeration cycle by circulating therefrigerant. In this example, the refrigerant circuit (10) includes acompressor (11), an outdoor heat exchanger (12), an outdoor expansionvalve (13), an indoor expansion valve (14), an indoor heat exchanger(15), and a four-way switching valve (16). The compressor (11), theoutdoor heat exchanger (12), the outdoor expansion valve (13), and thefour-way switching valve (16) are provided in an outdoor unit (3). Theindoor expansion valve (14) and the indoor heat exchanger (15) areprovided in an indoor unit (4). An indoor fan (17) which transfersoutdoor air to the outdoor heat exchanger (12) is provided in theoutdoor unit (3), and an indoor fan (18) which transfers indoor air tothe indoor heat exchanger (15) is provided in the indoor unit (4).

<<Compressor>>

The compressor (11) compresses the refrigerant and discharges thecompressed refrigerant. Further, the compressor (11) is configured suchthat the number of rotations (i.e., an operation frequency) of thecompressor (11) can be changed in response to control by the controller(100). For example, the compressor (11) includes a variable capacitycompressor (e.g., rotary type, swing type, and scroll type compressors)capable of adjusting the number of rotations using an inverter circuit(not shown) controlled by the controller (100).

<<Outdoor Heat Exchanger>>

The outdoor heat exchanger (12) is an air heat exchanger which exchangesheat between the outdoor air transferred by the indoor fan (17) and therefrigerant. For example, the outdoor heat exchanger (12) includes across-fin type fin-and-tube heat exchanger.

<<Outdoor Expansion Valve>>

The outdoor expansion valve (13) adjusts the pressure of therefrigerant. The outdoor expansion valve (13) is capable of adjusting adegree of its opening in response to the control by the controller(100). For example, the outdoor expansion valve (13) includes anelectronic expansion valve.

<<Indoor Expansion Valve>>

The indoor expansion valve (14) adjusts the pressure of the refrigerant.The indoor expansion valve (14) is capable of adjusting a degree of itsopening in response to the control by the controller (100). For example,the indoor expansion valve (14) includes an electronic expansion valve.

<<Indoor Heat Exchanger>>

The indoor heat exchanger (15) is an air heat exchanger which exchangesheat between indoor air transferred by the indoor fan (18) and therefrigerant. For example, the indoor heat exchanger (15) includes across-fin type fin-and-tube heat exchanger.

<<Four-Way Switching Valve>>

The four-way switching valve (16) has first to fourth ports. Thefour-way switching valve (16) can be set to a first state (the stateindicated by solid line in FIG. 1) and a second state (the stateindicated by broken line in FIG. 1) in response to the control by thecontroller (100).

<Pipe Connection in Refrigerant Circuit>

In this example, the first port of the four-way switching valve (16) isconnected to a discharge pipe of the compressor (11), and the third portof the four-way switching valve (16) is connected to a suction pipe ofthe compressor (11). Further, a gas-side end of the outdoor heatexchanger (12) and the fourth port of the four-way switching valve (16)are connected to each other by a first refrigerant pipe (P11). Theliquid-side end of the outdoor heat exchanger (12) and the outdoorexpansion valve (13) are connected to each other by a second refrigerantpipe (P12). The outdoor expansion valve (13) and the indoor expansionvalve (14) are connected to each other by a third refrigerant pipe(P13). The indoor expansion valve (14) and a liquid-side end of theindoor heat exchanger (15) are connected to each other by a fourthrefrigerant pipe (P14). A gas-side end of the indoor heat exchanger (15)and the second port of the four-way switching valve (16) are connectedto each other by a fifth refrigerant pipe (P15). The auxiliary heatexchanger (40) is connected to the second refrigerant pipe (P12). Thethermal storage heat exchanger (30) is connected to the thirdrefrigerant pipe (P13).

Further, in this example, the refrigerant circuit (10) includes a firstbypass pipe (PB1) and a second bypass pipe (PB2). One end of the firstbypass pipe (PB1) is connected to an intermediate portion of the firstrefrigerant pipe (P11), and the other end is connected to a firstintermediate portion (an intermediate portion located between theoutdoor expansion valve (13) and the thermal storage heat exchanger(30)) of the third refrigerant pipe (P13). One end of the second bypasspipe (PB2) is connected to an intermediate portion of the fifthrefrigerant pipe (P15), and the other end is connected to a secondintermediate portion (an intermediate portion located between thethermal storage heat exchanger (30) and the indoor expansion valve (14))of the third refrigerant pipe (P13).

<<Open/Close Valve and Pressure Relief Valve>>

In this example, a first open/close valve (V1), a second open/closevalve (V2), a third open/close valve (V3), and a pressure relief valve(V4) are provided in the refrigerant circuit (10). Each of theopen/close valves (V1, V2, V3) can be switched between an open state anda closed state in response to the control by the controller (100). Thefirst open/close valve (V1) and the second open/close valve (V2) aredisposed at the first bypass pipe (PB1) and the second bypass pipe(PB2), respectively. The third open/close valve (V3) is disposed betweenthe second intermediate portion (i.e., the intermediate portion at whichthe end of the second bypass pipe (PB2) is connected) of the thirdrefrigerant pipe (P13) and the indoor expansion valve (14). The pressurerelief valve (V4) is connected in parallel with the third open/closevalve (V3). When the pressure of the refrigerant on the side of thethird open/close valve (V3) closer to the indoor expansion valve (14)exceeds a predetermined value, the pressure relief valve (V4) is openedto allow the refrigerant to flow from the outdoor expansion valve (13)side to the thermal storage heat exchanger (30) side.

<Thermal Storage Circuit>

The thermal storage circuit (20) is a closed circuit filled with athermal storage medium, and stores heat by circulating the thermalstorage medium. The thermal storage heat exchanger (30) and theauxiliary heat exchanger (40) are connected to the thermal storagecircuit (20). Further, the retention portion (50) is provided in thethermal storage circuit (20). In this example, the thermal storagecircuit (20) includes a thermal storage tank (21) and a circulation pump(22).

<<Thermal Storage Tank>>

The thermal storage tank (21) is a hollow container, and stores thethermal storage medium. The thermal storage tank (21) is provided withan outlet (201) and an inlet (202). The outlet (201) is located higherthan the inlet (202). In this example, the thermal storage tank (21) isin a cylinder-like shape with its both ends closed, and is arranged suchthat the axial direction thereof is along a vertical direction.

<<Circulation Pump>>

The circulation pump (22) is provided to circulate the thermal storagemedium in the thermal storage circuit (20). Specifically, thecirculation pump (22) transfers the thermal storage medium, and iscapable of changing a transfer amount (i.e., a discharge amount) of thethermal storage medium in response to the control by the controller(100).

<Thermal Storage Medium>

The thermal storage medium is a thermal storage material which turnsinto slurry when cooled (i.e., a thermal storage material withfluidity). Examples of the thermal storage medium include atetra-n-butyl ammonium bromide (TBAB) aqueous solution, atrimethylolethane (TME) aqueous solution, paraffin slurry, etc. Forexample, if a tetra-n-butyl ammonium bromide aqueous solution is cooledand the temperature thereof becomes lower than a predeterminedsaturation temperature (i.e., a melting point), clathrate hydrates(i.e., crystals) comprised of tetra-n-butyl ammonium bromide and watermolecules are formed and the tetra-n-butyl ammonium bromide aqueoussolution turns into slurry with high viscosity. In contrast, when thetetra-n-butyl ammonium bromide aqueous solution in the form of slurry isheated and the temperature thereof becomes higher than the meltingpoint, the clathrate hydrates are melted and the tetra-n-butyl ammoniumbromide aqueous solution becomes a fluid with high fluidity. Here, themelting point of the tetra-n-butyl ammonium bromide aqueous solution (atemperature at which the clathrate hydrates are formed) is higher than0° C. (e.g., about 10° C.).

<Thermal Storage Heat Exchanger>

The thermal storage heat exchanger (30) exchanges heat between therefrigerant in the refrigerant circuit (10) and the thermal storagemedium in the thermal storage circuit (20). Specifically, the thermalstorage heat exchanger (30) uses the refrigerant in the refrigerantcircuit (10) as a heat sink when cold thermal energy (energy forcooling) is stored in the thermal storage medium in the thermal storagecircuit (20). In this example, the thermal storage heat exchanger (30)has a first path (31) connected in series with the refrigerant circuit(10) as part of the refrigerant circuit (10) and a second path (32)connected in series with the thermal storage circuit (20) as part of thethermal storage circuit (20), and exchanges heat between the refrigerantflowing in the first path (31) and the thermal storage medium flowing inthe second path (32). More specifically, the first path (31) of thethermal storage heat exchanger (30) is connected in series between theoutdoor expansion valve (13) and the indoor expansion valve (14)(specifically, between the first intermediate portion and the secondintermediate portion of the third refrigerant pipe (P13)) as part of thethird refrigerant pipe (P13) of the refrigerant circuit (10). The secondpath (32) of the thermal storage heat exchanger (30) is connected inseries between the outlet (201) and the inlet (202) of the thermalstorage tank (21) in the thermal storage circuit (20). In this example,the thermal storage heat exchanger (30) is provided in the outdoor unit(3).

<Auxiliary Heat Exchanger>

The auxiliary heat exchanger (40) exchanges heat between the refrigerantin the refrigerant circuit (10) and the thermal storage medium in thethermal storage circuit (20). Specifically, the auxiliary heat exchanger(40) uses the refrigerant in the refrigerant circuit (10) as a heatsource when cold thermal energy is stored in the thermal storage mediumin the thermal storage circuit (20). In this example, the auxiliary heatexchanger (40) has a first path (41) connected in series with therefrigerant circuit (10) as part of the refrigerant circuit (10) and asecond path (42) connected in series with the thermal storage circuit(20) as part of the thermal storage circuit (20), and exchanges heatwith the refrigerant flowing in the first path (41) and the thermalstorage medium flowing in the second path (42). More specifically, thefirst path (41) of the auxiliary heat exchanger (40) is connected inseries between the outdoor heat exchanger (12) and the outdoor expansionvalve (13) as part of the second refrigerant pipe (P12) of therefrigerant circuit (10). The second path (42) of the auxiliary heatexchanger (40) is connected in series between the outlet (201) of thethermal storage tank (21) and an inlet-side end of the second path (32)of the thermal storage heat exchanger (30) in the thermal storagecircuit (20). In this example, the auxiliary heat exchanger (40) isprovided in the outdoor unit (3).

<Retention Portion>

The retention portion (50) is provided in the thermal storage circuit(20) to retain crystals contained in the thermal storage medium. In thisexample, the retention portion (50) is provided between an outlet-sideend of the second path (42) of the auxiliary heat exchanger (40) and theinlet-side end of the second path (32) of the thermal storage heatexchanger (30) in the thermal storage circuit (20). In this example, athermal storage unit (2) includes the thermal storage tank (21), thecirculation pump (22), and the retention portion (50).

<Pipe Connection in Thermal Storage Circuit>

In this example, the outlet (201) of the thermal storage tank (21) andan inlet-side end of the second path (42) of the auxiliary heatexchanger (40) are connected to each other by a first thermal storagemedium pipe (P21); the outlet-side end of the second path (42) of theauxiliary heat exchanger (40) and the inlet-side end of the second path(32) of the thermal storage heat exchanger (30) are connected to eachother by a second thermal storage medium pipe (P22); and an outlet-sideend of the second path (32) of the thermal storage heat exchanger (30)and the inlet (202) of the thermal storage tank (21) are connected toeach other by a third thermal storage medium pipe (P23). The circulationpump (22) and the retention portion (50) are disposed in the secondthermal storage medium pipe (P22). Specifically, the circulation pump(22) is disposed between the second path (42) of the auxiliary heatexchanger (40) and the retention portion (50) in the second thermalstorage medium pipe (P22).

<Example Configuration of Retention Portion>

In this example, the retention portion (50) includes a retention filter(60) as shown in FIG. 2. The retention filter (60) is provided insidethe second thermal storage medium pipe (P22) (in this example, at aninside portion of the second thermal storage medium pipe (P22) betweenthe circulation pump (22) and the second path (32) of the thermalstorage heat exchanger (30)) to catch and retain crystals contained inthe thermal storage medium. The white arrows in FIG. 2 indicate a flowdirection of the thermal storage medium. That is, the crystals containedin the thermal storage medium having flowed out of the second path (42)of the auxiliary heat exchanger (40) are caught when the thermal storagemedium passes through the retention filter (60). Thereafter, the thermalstorage medium flows in the second path (32) of the thermal storage heatexchanger (30). That is, the crystals contained in the thermal storagemedium having flowed out of the second path (42) of the auxiliary heatexchanger (40) can be caught and retained by the retention filter (60).Further, the crystals of the thermal storage medium which are retainedby the retention filter (60) can be brought into contact with thehigh-temperature thermal storage medium having flowed out of the secondpath (42) of the auxiliary heat exchanger (40) (i.e., the thermalstorage medium heated in the auxiliary heat exchanger (40) by thehigh-temperature, high-pressure refrigerant) and be melted.

In this example, the retention filter (60) includes a mesh member whichcan catch the crystals contained in the thermal storage medium, andallow the thermal storage medium (specifically, an aqueous solution) topass therethrough. The retention filter (60) is in a cylinder-like shapeof which the cross sectional area is gradually reduced from an upstreamside to a downstream side in the flow direction of the thermal storagemedium.

<Cool Storage Mode>

Next, a cool storage mode of the air conditioner (1) will be describedwith reference to FIG. 3. In the cool storage mode, the refrigerantcircuit (10) performs an operation (a cool storage operation) in whichthe refrigerant is circulated such that the refrigerant condensed in theoutdoor heat exchanger (12) is evaporated in the first path (31) of thethermal storage heat exchanger (30). In this example, the refrigerantcircuit (10) performs a refrigeration cycle in which the outdoor heatexchanger (12) serves as a condenser and the thermal storage heatexchanger (30) serves as an evaporator. On the other hand, in thethermal storage circuit (20), the thermal storage medium is circulatedsuch that the thermal storage medium having flowed out from the outlet(201) of the thermal storage tank (21) sequentially passes through thesecond path (42) of the auxiliary heat exchanger (40), the retentionportion (50), and the second path (32) of the thermal storage heatexchanger (30), and thereafter flows into the inlet (202) of the thermalstorage tank (21).

In the refrigerant circuit (10), the four-way switching valve (16) isset to the first state; the first open/close valve (V1) and the thirdopen/close valve (V3) are set to a closed state; and the secondopen/close valve (V2) is set to an open state. Further, the indoorexpansion valve (14) is set to a fully-opened state, and the degree ofopening of the outdoor expansion valve (13) is set to a predetermineddegree of opening (a degree of opening which makes a degree of superheatof the refrigerant at the exit of the first path (31) of the thermalstorage heat exchanger (30) a predetermined target value). Then, thecompressor (11) and the indoor fan (17) are actuated.

The refrigerant discharged from the compressor (11) flows into theoutdoor heat exchanger (12) via the first refrigerant pipe (P11), anddissipates heat to the outdoor air and condenses while passing throughthe outdoor heat exchanger (12). The refrigerant condensed in theoutdoor heat exchanger (12) flows into the first path (41) of theauxiliary heat exchanger (40) via the second refrigerant pipe (P12), andheats the thermal storage medium flowing in the second path (42) of theauxiliary heat exchanger (40) while passing through the first path (41)of the auxiliary heat exchanger (40). The refrigerant having flowed outof the first path (41) of the auxiliary heat exchanger (40) flows intothe outdoor expansion valve (13), and is decompressed when passingthrough the outdoor expansion valve (13). The refrigerant decompressedby the outdoor expansion valve (13) flows into the first path (31) ofthe thermal storage heat exchanger (30) via the third refrigerant pipe(P13), and absorbs heat and evaporates while passing through the firstpath (31) of the thermal storage heat exchanger (30). The refrigeranthaving evaporated in the first path (31) of the thermal storage heatexchanger (30) is sucked into the compressor (11) via the second bypasspipe (PB2) and the fifth refrigerant pipe (P15), and is compressed.

On the other hand, the circulation pump (22) is actuated in the thermalstorage circuit (20). The thermal storage medium stored in the thermalstorage tank (21) flows into the second path (42) of the auxiliary heatexchanger (40) via the first thermal storage medium pipe (P21). Thethermal storage medium having flowed into the second path (42) of theauxiliary heat exchanger (40) is heated by the refrigerant flowing inthe first path (41) of the auxiliary heat exchanger (40), while passingthrough the second path (42) of the auxiliary heat exchanger (40). Thethermal storage medium heated by the auxiliary heat exchanger (40) flowsin the second thermal storage medium pipe (P22) and passes through thecirculation pump (22) and the retention portion (50), and then flowsinto the second path (32) of the thermal storage heat exchanger (30).The thermal storage medium having flowed into the second path (32) ofthe thermal storage heat exchanger (30) is cooled by the refrigerantflowing in the first path (31) of the thermal storage heat exchanger(30), while passing through the second path (32) of the thermal storageheat exchanger (30). The thermal storage medium cooled in the thermalstorage heat exchanger (30) flows into the thermal storage tank (21) viathe third thermal storage medium pipe (P23). The cold thermal energy isstored in the thermal storage medium in this manner.

<Use Cooling Mode>

Now, a use cooling mode of the air conditioner (1) will be describedwith reference to FIG. 4 and FIG. 5. A use cooling mode is an operationfor cooling a room by using the cold thermal energy stored in thethermal storage tank (21). In the use cooling mode, the refrigerantcircuit (10) performs an operation (a use cooling operation) in whichthe refrigerant is circulated such that the refrigerant having passedthrough the thermal storage heat exchanger (30) is evaporated in theindoor heat exchanger (15). On the other hand, in the thermal storagecircuit (20), the thermal storage medium is circulated such that thethermal storage medium having flowed out from the outlet (201) of thethermal storage tank (21) sequentially passes through the second path(42) of the auxiliary heat exchanger (40), the retention portion (50),and the second path (32) of the thermal storage heat exchanger (30), andthereafter flows into the inlet (202) of the thermal storage tank (21).In this example, the use cooling mode includes two types of modes, i.e.,a first use cooling mode and a second use cooling mode.

<<First Use Cooling Mode>>

First, a first use cooling mode of the air conditioner (1) will bedescribed with reference to FIG. 4. In the first use cooling mode, thecold thermal energy stored in the thermal storage tank (21) and the coldthermal energy obtained by the refrigeration cycle of the refrigerantcircuit (10) are used to cool the room. The refrigerant circuit (10)performs a refrigeration cycle in which the outdoor heat exchanger (12)serves as a condenser; the auxiliary heat exchanger (40) and the thermalstorage heat exchanger (30) serve as a subcooler (i.e., a radiator); andthe indoor heat exchanger (15) serves as an evaporator. On the otherhand, in the thermal storage circuit (20), the thermal storage medium iscirculated such that the thermal storage medium having flowed out of theoutlet (201) of the thermal storage tank (21) sequentially passesthrough the second path (42) of the auxiliary heat exchanger (40), theretention portion (50), and the second path (32) of the thermal storageheat exchanger (30), and flows in the inlet (202) of the thermal storagetank (21).

In the refrigerant circuit (10), the four-way switching valve (16) isset to the first state; the first open/close valve (V1) and the secondopen/close valve (V2) are set to a closed state; and the thirdopen/close valve (V3) is set to an open state. Further, the outdoorexpansion valve (13) is set to a fully-opened state, and a degree ofopening of the indoor expansion valve (14) is set to a predetermineddegree of opening (a degree of opening which makes a degree of superheatof the refrigerant at the exit of the indoor heat exchanger (15) apredetermined target value). Then, the compressor (11), the indoor fan(17), and the indoor fan (18) are actuated.

The refrigerant discharged from the compressor (11) flows into theoutdoor heat exchanger (12) via the first refrigerant pipe (P11), anddissipates heat to the outdoor air and condenses while passing throughthe outdoor heat exchanger (12). The refrigerant condensed in theoutdoor heat exchanger (12) flows into the first path (41) of theauxiliary heat exchanger (40) via the second refrigerant pipe (P12), andis cooled by the thermal storage medium flowing in the second path (42)of the auxiliary heat exchanger (40) while passing through the firstpath (41) of the auxiliary heat exchanger (40). The refrigerant havingflowed out of the second path (42) of the auxiliary heat exchanger (40)flows into the first path (31) of the thermal storage heat exchanger(30) via the third refrigerant pipe (P13), and is cooled by the thermalstorage medium flowing in the second path (32) of the thermal storageheat exchanger (30) while passing through the first path (31) of thethermal storage heat exchanger (30). The refrigerant having passedthrough the first path (31) of the thermal storage heat exchanger (30)flows into the indoor expansion valve (14) via the third refrigerantpipe (P13), and is decompressed when passing through the indoorexpansion valve (14). The refrigerant decompressed by the indoorexpansion valve (14) flows into the indoor heat exchanger (15) via thefourth refrigerant pipe (P14), and absorbs heat from the indoor air andevaporates while passing through the indoor heat exchanger (15). As aresult, the indoor air is cooled. The refrigerant having evaporated inthe indoor heat exchanger (15) is sucked into the compressor (11) viathe fifth refrigerant pipe (P15), and is compressed.

On the other hand, the circulation pump (22) is actuated in the thermalstorage circuit (20). The thermal storage medium stored in the thermalstorage tank (21) flows into the second path (42) of the auxiliary heatexchanger (40) via the first thermal storage medium pipe (P21), andabsorbs heat from the refrigerant flowing in the first path (41) of theauxiliary heat exchanger (40) while passing through the second path (42)of the auxiliary heat exchanger (40). The thermal storage medium havingflowed out of the second path (42) of the auxiliary heat exchanger (40)flows in the second thermal storage medium pipe (P22) and passes throughthe circulation pump (22) and the retention portion (50), and then flowsinto the second path (32) of the thermal storage heat exchanger (30).The thermal storage medium having flowed into the second path (32) ofthe thermal storage heat exchanger (30) absorbs heat from therefrigerant passing through the first path (31) of the thermal storageheat exchanger (30) while passing through the second path (32) of thethermal storage heat exchanger (30). The thermal storage medium havingflowed out of the second path (32) of the thermal storage heat exchanger(30) flows into the thermal storage tank (21) via the third thermalstorage medium pipe (P23). The cold thermal energy is given to therefrigerant from the thermal storage medium in this manner.

<<Second Use Cooling Mode>>

Now, a second use cooling mode of the air conditioner (1) will bedescribed with reference to FIG. 5. In the second use cooling mode, onlythe cold thermal energy stored in the thermal storage tank (21) is usedto cool the room. The refrigerant circuit (10) performs a refrigerationcycle in which the thermal storage heat exchanger (30) serves as acondenser and the indoor heat exchanger (15) serves as an evaporator. Onthe other hand, in the thermal storage circuit (20), the thermal storagemedium is circulated such that the thermal storage medium having flowedout from the outlet (201) of the thermal storage tank (21) sequentiallypasses through the second path (42) of the auxiliary heat exchanger(40), the retention portion (50), and the second path (32) of thethermal storage heat exchanger (30), and flows into the inlet (202) ofthe thermal storage tank (21).

In the refrigerant circuit (10), the four-way switching valve (16) isset to the first state; the second open/close valve (V2) is set to aclosed state; and the first open/close valve (V1) and the thirdopen/close valve (V3) are set to the open state. Further, the outdoorexpansion valve (13) is set to a fully-opened state, and a degree ofopening of the indoor expansion valve (14) is set to a predetermineddegree of opening (a degree of opening which makes a degree of superheatof the refrigerant at the exit of the indoor heat exchanger (15) apredetermined target value). Then, the compressor (11) and the indoorfan (18) are actuated. In this example, the compressor (11) severs as agas pump.

The refrigerant discharged from the compressor (11) flows into the firstpath (31) of the thermal storage heat exchanger (30) via the firstrefrigerant pipe (P11), the first bypass pipe (PB1), and the thirdrefrigerant pipe (P13), and dissipates heat to the thermal storagemedium flowing in the second path (32) of the thermal storage heatexchanger (30) and condenses while passing through the first path (31)of the thermal storage heat exchanger (30). The refrigerant havingflowed out of the first path (31) of the thermal storage heat exchanger(30) flows into the indoor expansion valve (14) via the thirdrefrigerant pipe (P13), and passes through the indoor expansion valve(14) and flows into the indoor heat exchanger (15). The refrigeranthaving flowed into the indoor heat exchanger (15) absorbs heat from theindoor air and evaporates while passing through the indoor heatexchanger (15). As a result, the indoor air is cooled. The refrigeranthaving evaporated in the indoor heat exchanger (15) is sucked into thecompressor (11) via the fifth refrigerant pipe (P15), and is compressed.

On the other hand, the circulation pump (22) is actuated in the thermalstorage circuit (20). The thermal storage medium stored in the thermalstorage tank (21) flows into the second path (42) of the auxiliary heatexchanger (40) via the first thermal storage medium pipe (P21). Thethermal storage medium having flowed out of the second path (42) of theauxiliary heat exchanger (40) flows in the second thermal storage mediumpipe (P22) and passes through the circulation pump (22) and theretention portion (50), and then flows into the second path (32) of thethermal storage heat exchanger (30). The thermal storage medium havingflowed into the second path (32) of the thermal storage heat exchanger(30) absorbs heat from the refrigerant passing through the first path(31) of the thermal storage heat exchanger (30) while passing throughthe second path (32) of the thermal storage heat exchanger (30). Thethermal storage medium having flowed out of the second path (32) of thethermal storage heat exchanger (30) flows into the thermal storage tank(21) via the third thermal storage medium pipe (P23). The cold thermalenergy is given to the refrigerant from the thermal storage medium inthis manner.

<Simple Cooling Mode>

Now, a simple cooling mode of the air conditioner (1) will be describedwith reference to FIG. 6. In the simple cooling mode, only the coldthermal energy which can be obtained by the refrigeration cycle of therefrigerant circuit (10) is used to cool the room. The refrigerantcircuit (10) performs a refrigeration cycle in which the outdoor heatexchanger (12) serves as a condenser and the indoor heat exchanger (15)serves as an evaporator. On the other hand, the thermal storage mediumis not circulated in the thermal storage circuit (20).

In the refrigerant circuit (10), the four-way switching valve (16) isset to the first state; the first open/close valve (V1) and the secondopen/close valve (V2) are set to the closed state; and the thirdopen/close valve (V3) is set to the open state. Further, the outdoorexpansion valve (13) is set to a fully-opened state, and a degree ofopening of the indoor expansion valve (14) is set to a predetermineddegree of opening (a degree of opening which makes a degree of superheatof the refrigerant at the exit of the indoor heat exchanger (15) apredetermined target value). Then, the compressor (11), the indoor fan(17), and the indoor fan (18) are actuated.

The refrigerant discharged from the compressor (11) flows into theoutdoor heat exchanger (12) via the first refrigerant pipe (P11), anddissipates heat to the outdoor air and condenses while passing throughthe outdoor heat exchanger (12). The refrigerant condensed in theoutdoor heat exchanger (12) flows into the indoor expansion valve (14)via the second refrigerant pipe (P12) and the third refrigerant pipe(P13), and is decompressed when passing through the indoor expansionvalve (14). The refrigerant decompressed by the indoor expansion valve(14) flows into the indoor heat exchanger (15) via the fourthrefrigerant pipe (P14), and absorbs heat from the indoor air andevaporates while passing through the indoor heat exchanger (15). As aresult, the indoor air is cooled. The refrigerant having evaporated inthe indoor heat exchanger (15) is sucked into the compressor (11) viathe fifth refrigerant pipe (P15), and is compressed.

<Simple Heating Mode>

Now, a simple heating mode of the air conditioner (1) will be describedwith reference to FIG. 7. In the simple heating mode, hot thermal energy(energy for heating) which can be obtained by the refrigeration cycle ofthe refrigerant circuit (10) is used to heat the room. The refrigerantcircuit (10) performs a refrigeration cycle in which the indoor heatexchanger (15) serves as a condenser and the outdoor heat exchanger (12)serves as an evaporator. On the other hand, the thermal storage mediumis not circulated in the thermal storage circuit (20).

In the refrigerant circuit (10), the four-way switching valve (16) isset to the second state; the first open/close valve (V1) and the secondopen/close valve (V2) are set to the closed state; and the thirdopen/close valve (V3) is set to the open state. Further, the indoorexpansion valve (14) is set to a fully-opened state, and a degree ofopening of the outdoor expansion valve (13) is set to a predetermineddegree of opening (a degree of opening which makes a degree of superheatof the refrigerant at the exit of the outdoor heat exchanger (12) apredetermined target value). Then, the compressor (11), the indoor fan(17), and the indoor fan (18) are actuated.

The refrigerant discharged from the compressor (11) flows into theindoor heat exchanger (15) via the fifth refrigerant pipe (P15), anddissipates heat to the indoor air and condenses while passing throughthe indoor heat exchanger (15). As a result, the indoor air is heated.The refrigerant condensed in the indoor heat exchanger (15) flows intothe outdoor expansion valve (13) via the fourth refrigerant pipe (P14)and the third refrigerant pipe (P13), and is decompressed when passingthrough the outdoor expansion valve (13).

The refrigerant decompressed by the outdoor expansion valve (13) flowsinto the outdoor heat exchanger (12) via the second refrigerant pipe(P12), and absorbs heat from the outdoor air and evaporates whilepassing through the heat exchanger (12). The refrigerant havingevaporated in the outdoor heat exchanger (12) is sucked into thecompressor (11) via the first refrigerant pipe (P11), and is compressed.

<Behavior of Thermal Storage Medium in Cool Storage Mode>

Now, the behavior of the thermal storage medium in the thermal storagecircuit (20) during a thermal storage mode will be described withreference to FIG. 3 and FIG. 8. In FIG. 8, the vertical axis indicates atemperature of the thermal storage medium, and the horizontal axisindicates time. That is, the length of the horizontal axis in FIG. 8corresponds to a flow time of the thermal storage medium (i.e., anecessary period of time from when the thermal storage medium flows in,to when the thermal storage medium flows out) in the respective elementsof the thermal storage circuit (20) (e.g., the auxiliary heat exchanger(40), the circulation pump (22), and the retention portion (50)). InFIG. 8, for simplicity of explanation, temperature changes in betweenthe elements of the thermal storage circuit (20) are not shown.

The solid line (L11) in FIG. 8 shows a temperature change of the thermalstorage medium in the thermal storage circuit (20) of the presentembodiment. In this example, a melting point temperature of the thermalstorage medium is 11.6° C., and a temperature of the thermal storagemedium stored in the thermal storage tank (21) is equal to the meltingpoint temperature of the thermal storage medium, that is, 11.6° C. Thetemperatures shown below are all examples.

When the circulation pump (22) is actuated in the cool storage mode asillustrated in FIG. 3, the thermal storage medium stored in the thermalstorage tank (21) flows into the second path (42) of the auxiliary heatexchanger (40) via the first thermal storage medium pipe (P21), and isheated by the refrigerant flowing in the first path (41) of theauxiliary heat exchanger (40) (i.e., the high-temperature, high-pressurerefrigerant flowing out of the outdoor heat exchanger (12)), whilepassing through the second path (42) of the auxiliary heat exchanger(40). Thus, as indicated by solid line (L11) in FIG. 8, the temperatureof the thermal storage medium is increased from a temperature equal tothe melting point temperature (11.6° C.) to a temperature (12.9° C.)higher than the melting point temperature. The crystals contained in thethermal storage medium are melted by heating the thermal storage mediumto a temperature higher than the melting point temperature of thethermal storage medium.

Next, the thermal storage medium having flowed out of the second path(42) of the auxiliary heat exchanger (40) flows into the circulationpump (22) via the second thermal storage medium pipe (P22), and isheated by the heat generated by driving the circulation pump (22), whilepassing through the circulation pump (22). Thus, as indicated by solidline (L11) in FIG. 8, the temperature of the thermal storage medium isincreased from the temperature (12.9° C.) higher than the melting pointtemperature to a temperature (13.0° C.) much higher than the meltingpoint temperature.

Next, the thermal storage medium having flowed out of the circulationpump (22) flows into the retention portion (50) via the second thermalstorage medium pipe (P22), and is retained. Here, the thermal storagemedium heated in the auxiliary heat exchanger (40) and the circulationpump (22) continues to flow in the retention portion (50). Thus, asindicated by solid line (L11) in FIG. 8, the temperature of the thermalstorage medium in the retention portion (50) is maintained at thetemperature (that is 13.0° C. in this example) higher than the meltingpoint temperature. Melting of the crystals contained in the thermalstorage medium continues to proceed by continuously heating the thermalstorage medium to maintain the temperature of the thermal storage mediumat a temperature higher than the melting temperature of the thermalstorage medium, as described above.

Next, the thermal storage medium having flowed out of the retentionportion (50) flows into the second path (32) of the thermal storage heatexchanger (30) via the second thermal storage medium pipe (P22), and iscooled by the refrigerant flowing in the first path (31) of the thermalstorage heat exchanger (30) (i.e., the refrigerant which absorbs heatand evaporates in the first path (31) of the thermal storage heatexchanger (30)), while passing through the second path (32) of thethermal storage heat exchanger (30). Thus, the temperature of thethermal storage medium is reduced from the temperature (13.0° C.) higherthan the melting point temperature to a temperature (e.g., 9° C. that isnot shown in FIG. 8) lower than the melting point temperature.

<Comparison between the Present Embodiment and Comparative Example>

Now, the air conditioner (1) of the present embodiment and comparativeexamples (the first comparative example and the second comparativeexample) of the air conditioner (1) will be compared and described withreference to FIG. 8. The upper broken line (L21) in FIG. 8 shows changesin temperature of the thermal storage medium in the thermal storagecircuit (20) in the case where the retention portion (50) is notprovided in the air conditioner (1) (the first comparative example), andthe lower broken line (L22) in FIG. 8 shows changes in temperature ofthe thermal storage medium in the thermal storage circuit (20) in thecase where the retention portion (50) is not provided in the airconditioner (1) and the auxiliary heat exchanger (40) has low heatexchange properties (the second comparative example).

In the case where the retention portion (50) is not provided in the airconditioner (1) (in the case of the first comparative example), thethermal storage medium having flowed out of the thermal storage tank(21) sequentially passes through the second path (42) of the auxiliaryheat exchanger (40) and the circulation pump (22), and thereafter flowsinto the second path (32) of the thermal storage heat exchanger (30). Inthis case, as indicated by the upper broken line (L21) in FIG. 8, theflow time of the thermal storage medium in the second path (42) of theauxiliary heat exchanger (40) is extended to ensure crystal heating time(time of heating and melting of the crystals of the thermal storagemedium) in the auxiliary heat exchanger (40). This means that the secondpath (42) of the auxiliary heat exchanger (40) has a long length,causing an increase in size of the auxiliary heat exchanger (40).Further, as indicated by the upper broken line (L21) in FIG. 8, thethermal storage medium is heated more than necessary in the second path(42) of the auxiliary heat exchanger (40), and therefore, the thermalenergy is wasted in the auxiliary heat exchanger (40).

If the heat exchange properties of the auxiliary heat exchanger (40) arereduced to reduce the waste of the thermal energy in the auxiliary heatexchanger (40) in the air conditioner (1) where the retention portion(50) is not provided (i.e., in the case of the second comparativeexample), as indicated by the lower broken line (L22) in FIG. 8, it ispossible to prevent unnecessary heating of the thermal storage medium inthe second path (42) of the auxiliary heat exchanger (40). However, inthis case, as well, the flow time of the thermal storage medium in thesecond path (42) of the auxiliary heat exchanger (40) needs to beextended to ensure crystal heating time (time of heating and melting ofthe crystals of the thermal storage medium) in the auxiliary heatexchanger (40). As a result, the auxiliary heat exchanger (40) isincreased in size.

In contrast, in the air conditioner (1) of the present embodiment, it ispossible to ensure crystal heating time (time of heating and melting ofthe crystals of the thermal storage medium) due to time in which thethermal storage medium is retained in the retention portion (50), asindicated by the solid line (L11) in FIG. 8. Therefore, the second path(42) of the auxiliary heat exchanger (40) does not need to be elongated.As a result, it is possible to reduce an increase in size of theauxiliary heat exchanger (40).

<Effects of the Embodiment>

As described above, due to the provision of the auxiliary heat exchanger(40), the thermal storage medium on the upstream side of the second path(32) of the thermal storage heat exchanger (30) (i.e., the thermalstorage medium flowing into the second path (32) of the thermal storageheat exchanger (30)) can be heated by the high-temperature,high-pressure refrigerant that has been condensed in the air heatexchanger (12) of the refrigerant circuit (10). Therefore, the crystalscontained in the thermal storage medium on the upstream side of thesecond path (32) of the thermal storage heat exchanger (30) can bemelted.

Further, due to the provision of the retention portion (50), thecrystals of the thermal storage medium remaining in the thermal storagemedium having flowed out of the second path (42) of the auxiliary heatexchanger (40) (i.e., the crystals which have not been melted in theauxiliary heat exchanger (40)) can be retained in the retention portion(50). Moreover, the crystals of the thermal storage medium which areretained in the retention portion (50) can be brought into contact withand be melted by the high-temperature thermal storage medium havingflowed out of the second path (42) of the auxiliary heat exchanger (40)(i.e., the thermal storage medium heated by the high-temperature,high-pressure refrigerant in the auxiliary heat exchanger (40)).

Since the crystal heating time (i.e., the time of heating and melting ofthe crystals contained in the thermal storage medium) on the upstreamside of the second path (32) of the thermal storage heat exchanger (30)can be extended, it is possible to reduce the crystals of the thermalstorage medium flowing into the thermal storage heat exchanger (30).

Further, the provision of the circulation pump (22) in between thesecond path (42) of the auxiliary heat exchanger (40) and the retentionportion (50) in the thermal storage circuit (20) allows the crystals ofthe thermal storage medium remaining in the thermal storage mediumflowing out of the second path (42) of the auxiliary heat exchanger (40)to be melted by the heat generated by driving the circulation pump (22).Thus, the crystal heating time on the upstream side of the second path(32) of the thermal storage heat exchanger (30) can be further extended,and the crystals of the thermal storage medium flowing into the thermalstorage heat exchanger (30) can be further reduced.

The concentration of slurry (the concentration of the crystals) of thethermal storage medium stored in the thermal storage tank (21) tends tobe increased from an upper portion to a lower portion of the thermalstorage tank (21). Thus, flowing out of the crystals of the thermalstorage medium stored in the thermal storage tank (21) through theoutlet (201) of the thermal storage tank (21) can be reduced byproviding the outlet (201) of the thermal storage tank (21) at alocation higher than the inlet (202). As a result, the crystals of thethermal storage medium which flow into the thermal storage heatexchanger (30) can be further reduced.

Further, since the crystals of the thermal storage medium which flowinto the thermal storage heat exchanger (30) can be reduced, it ispossible to delay crystallization of the thermal storage medium in thesecond path (32) of the thermal storage heat exchanger (30). It istherefore possible to extend the time from the start of the cool storagemode until the thermal storage medium flow less easily in the secondpath (32) of the thermal storage heat exchanger (30) due to thecrystallization of the thermal storage medium (e.g., the time until thesecond path (32) of the thermal storage heat exchanger (30) is clogged).

Further, since the cold thermal energy stored in the thermal storagemedium in the cool storage mode can be used in the use cooling mode, itis possible to reduce power consumption of the cooling operation of theair conditioner (1).

<Heating Temperature of Auxiliary Heat Exchanger in Cool Storage Mode>

It is preferable that parameters of the air conditioner (1) (e.g., thelength of the second path (42) of the auxiliary heat exchanger (40), andthe length of a heat-transfer pipe of the outdoor heat exchanger (12))and operational conditions of the air conditioner (1) (e.g., the numberof rotations of the compressor (11), and a degree of opening of theoutdoor expansion valve (13)) are determined such that when the thermalstorage medium flowing in the second path (42) of the auxiliary heatexchanger (40) is heated in the cool storage mode by the refrigerantflowing in the first path (41) of the auxiliary heat exchanger (40) (thehigh-temperature, high-pressure refrigerant which has been condensed inthe outdoor heat exchanger (12)), the temperature of the thermal storagemedium becomes a temperature higher than the melting point temperatureof the thermal storage medium (e.g., a temperature higher than themelting point temperature by 1° C. or more). In the air conditionerhaving the above configurations, the crystals contained in the thermalstorage medium on the upstream side of the thermal storage heatexchanger (30) can be reliably melted in the cool storage mode.

<First Variation of Retention Portion>

As shown in FIG. 9, the retention portion (50) may include a retentiontank (70). The retention tank (70) is a hollow container, and retainsthe thermal storage medium. The retention tank (70) is provided with aninlet (701) and an outlet (702). In this example, the height (H2) of aportion where the outlet (702) is formed is different from the height(H1) of a portion where the inlet (701) is formed. Specifically, theheight (H2) of the outlet (702) is higher than the height (H1) of theinlet (701). Alternatively, the height (H2) of the outlet (702) may beequal to the height (H1) of the inlet (701). In this example, theretention tank (70) is in a cylinder-like shape with its both endsclosed, and is arranged such that the axial direction thereof is along avertical direction. Further, the retention tank (70) is incorporated inthe second thermal storage medium pipe (P22) of the thermal storagecircuit (20). Specifically, the second thermal storage medium pipe (P22)includes an upstream pipe (P31) and a downstream pipe (P32). The inlet(701) of the retention tank (70) is connected to the outlet-side end ofthe second path (42) of the auxiliary heat exchanger (40) by theupstream pipe (P31). The outlet (702) of the retention tank (70) isconnected to the inlet-side end of the second path (32) of the thermalstorage heat exchanger (30) by the downstream pipe (P32).

In this example, the thermal storage medium having flowed out of thesecond path (42) of the auxiliary heat exchanger (40) flows into thethermal storage tank (21) through the inlet (701) of the retention tank(70) and is retained, and thereafter flows out through the outlet (702)of the retention tank (70) and flows into the second path (32) of thethermal storage heat exchanger (30). Thus, the crystals remaining in thethermal storage medium having flowed out of the second path (42) of theauxiliary heat exchanger (40) can be retained in the retention tank (70)together with the thermal storage medium. Moreover, the crystals of thethermal storage medium which are retained in the retention tank (70) canbe brought into contact with and be melted by the high-temperaturethermal storage medium having flowed out of the second path (42) of theauxiliary heat exchanger (40).

<Effects of Retention Portion of First Variation>

In the compressor having the above configurations, as well, it ispossible to extend the crystal heating time (time of heating and meltingof the crystals contained in the thermal storage medium) on the upstreamside of the second path (32) of the thermal storage heat exchanger (30).It is therefore possible to reduce the crystals of the thermal storagemedium flowing into the thermal storage heat exchanger (30).

<Second Variation of Retention Portion>

As shown in FIG. 10, the retention portion (50) may include a retentionpipe (80). A middle portion (81) of the retention pipe (80) has a largercross-sectional area (A1) than a cross-sectional area (A2) of each ofend portions (82, 83) of the retention pipe (80). In this example, themiddle portion (81) of the retention pipe (80) is in a cylinder-likeshape, and each of the end portions (82, 83) of the retention pipe (80)is tapered such that the cross-sectional area thereof is graduallyreduced from the cross-sectional area (A1) to the cross-sectional area(A2) in a direction from a base to a tip. Further, the retention pipe(80) is incorporated in the second thermal storage medium pipe (P22) ofthe thermal storage circuit (20). Specifically, the second thermalstorage medium pipe (P22) includes the upstream pipe (P31) and thedownstream pipe (P32). The first end portion (82) of the retention pipe(80) is connected to the outlet-side end of the second path (42) of theauxiliary heat exchanger (40) by the upstream pipe (P31). The second endportion (83) of the retention pipe (80) is connected to the inlet-sideend of the second path (32) of the thermal storage heat exchanger (30)by the downstream pipe (P32).

In this example, the flow speed of the thermal storage medium in themiddle portion (81) of the retention pipe (80) can be reduced since thecross-sectional area (A1) of the middle portion (81) is larger than thecross-sectional area (A2) of each of the end portions (82, 83). Thus,the thermal storage medium having flowed out of the second path (42) ofthe auxiliary heat exchanger (40) flows into the retention pipe (80)through the first end portion (82) and is retained in the middle portion(81), and thereafter flows out through the second end portion (83) andflows into the second path (32) of the thermal storage heat exchanger(30). The crystals of the thermal storage medium which remain in thethermal storage medium having flowed out of the second path (42) of theauxiliary heat exchanger (40) can be retained in the retention pipe (80)together with the thermal storage medium having flowed out of the secondpath (42). Further, the crystals of the thermal storage medium which areretained in the retention pipe (80) can be brought into contact with andbe melted by the high-temperature thermal storage medium having flowedout of the second path (42) of the auxiliary heat exchanger (40).

<Effects of Retention Portion of Second Variation>

In the compressor having the above configurations, as well, it ispossible to extend the crystal heating time (time of heating and meltingof the crystals contained in the thermal storage medium) on the upstreamside of the second path (32) of the thermal storage heat exchanger (30).It is therefore possible to reduce the crystals of the thermal storagemedium flowing into the thermal storage heat exchanger (30).

<Other Embodiments>

In the above embodiments, an example in which the retention portion (50)includes one of the retention filter (60), the retention tank (70), orthe retention pipe (80) has been described, but the retention portion(50) may include a combination of at least two of the retention filter(60), the retention tank (70), and the retention pipe (80). For example,as shown in FIG. 11, the retention portion (50) may include theretention filter (60) and the retention pipe (80). In this example, theretention filter (60) is provided inside the retention pipe (80).

Further, an example has been described in which, during the second usecooling mode (FIG. 5), the refrigerant is circulated such that therefrigerant having passed through the first path (31) of the thermalstorage heat exchanger (30) is evaporated in the outdoor heat exchanger(15). However, the refrigerant circuit (10) may perform an operation inwhich the refrigerant is circulated such that the refrigerant havingpassed through both of the first path (41) of the auxiliary heatexchanger (40) and the first path (31) of the thermal storage heatexchanger (30) is evaporated in the outdoor heat exchanger (15). In thiscase, as shown in FIG. 12, one end of the first bypass pipe (PB1) isconnected to an intermediate portion of the first refrigerant pipe(P11), and the other end of the first bypass pipe (PB1) is connected toan intermediate portion of the second refrigerant pipe (P12) (anintermediate portion located between the outdoor heat exchanger (12) andthe auxiliary heat exchanger (40)) in the refrigerant circuit (10).Further, a fourth open/close valve (V5) is provided between theintermediate portion (the portion where the one end of the first bypasspipe (PB1) is connected) of the first refrigerant pipe (P11) and theoutdoor heat exchanger (12). The fourth open/close valve (V5) is capableof switching between an open state and a closed state in response to thecontrol by the controller (100). The fourth open/close valve (V5) is setto the closed state in the second use cooling mode, and is set to theopen state in the other operations (i.e., the cool storage mode, thefirst use cooling mode, the simple cooling mode, and the simple heatingmode). The other configurations are similar to those of the airconditioner (1) shown in FIG. 1.

In the second use cooling mode of the air conditioner (1) shown in FIG.12, the four-way switching valve (16) is set to the first state; thesecond open/close valve (V2) and the fourth open/close valve (V5) areset to the closed state; and the first open/close valve (V1) and thethird open/close valve (V3) are set to the open state, in therefrigerant circuit (10). Further, the outdoor expansion valve (13) isset to a fully-opened state; the degree of opening of the indoorexpansion valve (14) is set to a predetermined degree of opening (adegree of opening which makes a degree of superheat of the refrigerantat the exit of the indoor heat exchanger (15) a predetermined targetvalue). Then, the compressor (11) and the indoor fan (18) are actuated.In this example, the compressor (11) severs as a gas pump.

In the second use cooling mode shown in FIG. 12, the refrigerantdischarged from the compressor (11) flows into the first path (41) ofthe auxiliary heat exchanger (40) via the first refrigerant pipe (P11)and the first bypass pipe (PB1), and dissipates heat to the thermalstorage medium flowing in the second path (42) of the auxiliary heatexchanger (40) and condenses, while passing through the first path (41)of the auxiliary heat exchanger (40). The refrigerant having flowed outof the first path (41) of the auxiliary heat exchanger (40) flows intothe first path (31) of the thermal storage heat exchanger (30) via thethird refrigerant pipe (P13), and dissipates heat to the thermal storagemedium flowing in the second path (32) of the thermal storage heatexchanger (30) and condenses, while passing through the first path (31)of the thermal storage heat exchanger (30). The refrigerant havingflowed out of the first path (31) of the thermal storage heat exchanger(30) flows into the indoor expansion valve (14) via the thirdrefrigerant pipe (P13), and passes through the indoor expansion valve(14) and flows into the indoor heat exchanger (15). The refrigeranthaving flowed into the indoor heat exchanger (15) absorbs heat from theindoor air and evaporates while passing through the indoor heatexchanger (15). As a result, the indoor air is cooled. The refrigeranthaving evaporated in the indoor heat exchanger (15) is sucked into thecompressor (11) via the fifth refrigerant pipe (P15) and is compressed.

On the other hand, the circulation pump (22) is actuated in the thermalstorage circuit (20). The thermal storage medium stored in the thermalstorage tank (21) flows into the second path (42) of the auxiliary heatexchanger (40) via the first thermal storage medium pipe (P21), andabsorbs heat from the refrigerant passing through the first path (41) ofthe auxiliary heat exchanger (40), while passing through the second path(42) of the auxiliary heat exchanger (40). The thermal storage mediumhaving flowed out of the second path (42) of the auxiliary heatexchanger (40) passes through the second thermal storage medium pipe(P22), the circulation pump (22), and the retention portion (50), andthereafter flows into the second path (32) of the thermal storage heatexchanger (30). The thermal storage medium having flowed into the secondpath (32) of the thermal storage heat exchanger (30) absorbs heat fromthe refrigerant passing through the first path (31) of the thermalstorage heat exchanger (30), while passing through the second path (32)of the thermal storage heat exchanger (30). The thermal storage mediumhaving flowed out of the second path (32) of the thermal storage heatexchanger (30) flows into the thermal storage tank (21) via the thirdthermal storage medium pipe (P23). The cold thermal energy is given tothe refrigerant from the thermal storage medium in this manner.

The above embodiments may be appropriately combined for application tothe air conditioner.

The above embodiments are merely preferred examples in nature, and arenot intended to limit the scope, applications, and use of the invention.

What is claimed is:
 1. An air conditioner, comprising: a refrigerantcircuit having an air heat exchanger which exchanges heat between arefrigerant and air; a thermal storage circuit having a thermal storagetank configured to store a thermal storage medium which turns intoslurry when cooled, and a circulation pump provided to circulate thethermal storage medium; a thermal storage heat exchanger which isconnected to the refrigerant circuit and to the thermal storage circuit,and exchanges heat between the refrigerant flowing in the refrigerantcircuit and the thermal storage medium flowing in the thermal storagecircuit; an auxiliary heat exchanger which is connected to therefrigerant circuit and to the thermal storage circuit, and exchangesheat between the refrigerant flowing in the refrigerant circuit and thethermal storage medium flowing in the thermal storage circuit; and aretention portion provided in the thermal storage circuit to retaincrystals contained in the thermal storage medium, wherein therefrigerant circuit performs a cool storage operation in which therefrigerant is circulated such that the refrigerant which has beencondensed in the air heat exchanger and passed through the auxiliaryheat exchanger is evaporated in the thermal storage heat exchanger, andin the thermal storage circuit during the cool storage operation, thethermal storage medium is circulated such that the thermal storagemedium having flowed out from an outlet of the thermal storage tanksequentially passes through the auxiliary heat exchanger, the retentionportion, and the thermal storage heat exchanger and flows into an inletof the thermal storage tank.
 2. The air conditioner of claim 1, whereinthe retention portion includes a retention filter which catches andretains the crystals contained in the thermal storage medium.
 3. The airconditioner of claim 1, wherein the retention portion includes aretention tank which is provided with an inlet and an outlet, and whichretains the thermal storage medium flowing therein through the inlet anddischarges the thermal storage medium retained therein through theoutlet.
 4. The air conditioner of claim 1, wherein the retention portionincludes a retention pipe of which a middle portion has a largercross-sectional area than a cross-sectional area of each of its endportions.
 5. The air conditioner of claim 1, wherein the circulationpump is provided between the auxiliary heat exchanger and the retentionportion in the thermal storage circuit.
 6. The air conditioner of claim1, wherein the outlet of the thermal storage tank is provided at alocation higher than the inlet of the thermal storage tank.
 7. The airconditioner of claim 1, wherein the air heat exchanger is an outdoorheat exchanger, the refrigerant circuit includes the air heat exchangerand an indoor heat exchanger, and performs the cool storage operationand a use cooling operation in which the refrigerant is circulated suchthat the refrigerant having passed through the thermal storage heatexchanger is evaporated in the indoor heat exchanger, in the thermalstorage circuit during any one of the cool storage operation or the usecooling operation, the thermal storage medium is circulated such thatthe thermal storage medium having flowed out from the outlet of thethermal storage tank sequentially passes through the auxiliary heatexchanger, the retention portion, and the thermal storage heat exchangerand flows into the inlet of the thermal storage tank.
 8. The airconditioner of claim 2, wherein the circulation pump is provided betweenthe auxiliary heat exchanger and the retention portion in the thermalstorage circuit.
 9. The air conditioner of claim 2, wherein the outletof the thermal storage tank is provided at a location higher than theinlet of the thermal storage tank.
 10. The air conditioner of claim 2,wherein the air heat exchanger is an outdoor heat exchanger, therefrigerant circuit includes the air heat exchanger and an indoor heatexchanger, and performs the cool storage operation and a use coolingoperation in which the refrigerant is circulated such that therefrigerant having passed through the thermal storage heat exchanger isevaporated in the indoor heat exchanger, in the thermal storage circuitduring any one of the cool storage operation or the use coolingoperation, the thermal storage medium is circulated such that thethermal storage medium having flowed out from the outlet of the thermalstorage tank sequentially passes through the auxiliary heat exchanger,the retention portion, and the thermal storage heat exchanger and flowsinto the inlet of the thermal storage tank.
 11. The air conditioner ofclaim 3, wherein the circulation pump is provided between the auxiliaryheat exchanger and the retention portion in the thermal storage circuit.12. The air conditioner of claim 3, wherein the outlet of the thermalstorage tank is provided at a location higher than the inlet of thethermal storage tank.
 13. The air conditioner of claim 3, wherein theair heat exchanger is an outdoor heat exchanger, the refrigerant circuitincludes the air heat exchanger and an indoor heat exchanger, andperforms the cool storage operation and a use cooling operation in whichthe refrigerant is circulated such that the refrigerant having passedthrough the thermal storage heat exchanger is evaporated in the indoorheat exchanger, in the thermal storage circuit during any one of thecool storage operation or the use cooling operation, the thermal storagemedium is circulated such that the thermal storage medium having flowedout from the outlet of the thermal storage tank sequentially passesthrough the auxiliary heat exchanger, the retention portion, and thethermal storage heat exchanger and flows into the inlet of the thermalstorage tank.
 14. The air conditioner of claim 4, wherein thecirculation pump is provided between the auxiliary heat exchanger andthe retention portion in the thermal storage circuit.
 15. The airconditioner of claim 4, wherein the outlet of the thermal storage tankis provided at a location higher than the inlet of the thermal storagetank.
 16. The air conditioner of claim 4, wherein the air heat exchangeris an outdoor heat exchanger, the refrigerant circuit includes the airheat exchanger and an indoor heat exchanger, and performs the coolstorage operation and a use cooling operation in which the refrigerantis circulated such that the refrigerant having passed through thethermal storage heat exchanger is evaporated in the indoor heatexchanger, in the thermal storage circuit during any one of the coolstorage operation or the use cooling operation, the thermal storagemedium is circulated such that the thermal storage medium having flowedout from the outlet of the thermal storage tank sequentially passesthrough the auxiliary heat exchanger, the retention portion, and thethermal storage heat exchanger and flows into the inlet of the thermalstorage tank.
 17. The air conditioner of claim 5, wherein the outlet ofthe thermal storage tank is provided at a location higher than the inletof the thermal storage tank.
 18. The air conditioner of claim 17,wherein the air heat exchanger is an outdoor heat exchanger, therefrigerant circuit includes the air heat exchanger and an indoor heatexchanger, and performs the cool storage operation and a use coolingoperation in which the refrigerant is circulated such that therefrigerant having passed through the thermal storage heat exchanger isevaporated in the indoor heat exchanger, in the thermal storage circuitduring any one of the cool storage operation or the use coolingoperation, the thermal storage medium is circulated such that thethermal storage medium having flowed out from the outlet of the thermalstorage tank sequentially passes through the auxiliary heat exchanger,the retention portion, and the thermal storage heat exchanger and flowsinto the inlet of the thermal storage tank.
 19. The air conditioner ofclaim 5, wherein the air heat exchanger is an outdoor heat exchanger,the refrigerant circuit includes the air heat exchanger and an indoorheat exchanger, and performs the cool storage operation and a usecooling operation in which the refrigerant is circulated such that therefrigerant having passed through the thermal storage heat exchanger isevaporated in the indoor heat exchanger, in the thermal storage circuitduring any one of the cool storage operation or the use coolingoperation, the thermal storage medium is circulated such that thethermal storage medium having flowed out from the outlet of the thermalstorage tank sequentially passes through the auxiliary heat exchanger,the retention portion, and the thermal storage heat exchanger and flowsinto the inlet of the thermal storage tank.
 20. The air conditioner ofclaim 6, wherein the air heat exchanger is an outdoor heat exchanger,the refrigerant circuit includes the air heat exchanger and an indoorheat exchanger, and performs the cool storage operation and a usecooling operation in which the refrigerant is circulated such that therefrigerant having passed through the thermal storage heat exchanger isevaporated in the indoor heat exchanger, in the thermal storage circuitduring any one of the cool storage operation or the use coolingoperation, the thermal storage medium is circulated such that thethermal storage medium having flowed out from the outlet of the thermalstorage tank sequentially passes through the auxiliary heat exchanger,the retention portion, and the thermal storage heat exchanger and flowsinto the inlet of the thermal storage tank.